Analgesics and Anti-inflammatory Drugs Practice Questions

Q: Which of the following statements about bradykinin is true?

Causes pain. **Explanation:** Bradykinin is a potent inflammatory nonapeptide belonging to the kinin system. It plays a central role in the pathophysiology of pain and inflammation. **1. Why Option A is Correct:** Bradykinin is one of the most potent endogenous algogenic (pain-producing) substances. It stimulates **B2 receptors** on sensory nerve endings (nociceptors), leading to the sensation of sharp, localized pain. Furthermore, it sensitizes these nerve endings to other stimuli (hyperalgesia) by stimulating the release of prostaglandins. **2. Why the Other Options are Incorrect:** * **B. Causes bronchodilation:** Incorrect. Bradykinin is a potent **bronchoconstrictor**, particularly in patients with asthma. It acts via B2 receptors to contract airway smooth muscle. * **C. Causes vasoconstriction:** Incorrect. Bradykinin is a powerful **vasodilator** in most vascular beds (via nitric oxide and PGI2 release). However, it does cause contraction of non-vascular smooth muscle (like the gut and bronchi). * **D. Decreases vascular permeability:** Incorrect. Bradykinin **increases vascular permeability** by causing contraction of endothelial cells in post-capillary venules, leading to edema (a hallmark of angioedema). **Clinical Pearls for NEET-PG:** * **ACE Inhibitors (ACEIs):** ACE (also known as Kinanase II) is responsible for the degradation of bradykinin. ACEIs lead to increased bradykinin levels, which is the primary cause of the **dry cough** and **angioedema** associated with these drugs. * **Icatibant:** A selective B2 receptor antagonist used in the treatment of acute attacks of Hereditary Angioedema (HAE). * **Receptors:** B1 receptors are induced during chronic inflammation, while B2 receptors are constitutively expressed and mediate most acute effects.

Q: Which opioid is contraindicated in patients taking MAO inhibitors?

Fentanyl. ### Explanation **Correct Option: C. Fentanyl** The interaction between certain opioids and **Monoamine Oxidase Inhibitors (MAOIs)** can lead to a life-threatening condition known as **Serotonin Syndrome**. This occurs because some opioids act as weak serotonin reuptake inhibitors. When combined with MAOIs (which prevent the breakdown of serotonin), there is a massive accumulation of serotonin in the synaptic cleft. Fentanyl, along with **Pethidine (Meperidine)**, Tramadol, and Methadone, is known to have serotonergic activity. The interaction typically manifests as the "Excitatory Type" reaction, characterized by agitation, hyperpyrexia, muscular rigidity, and seizures. **Why other options are incorrect:** * **A. Codeine & B. Morphine:** These are phenanthrene derivatives. While they can cause a "Depressive Type" reaction (potentiation of opioid effects like respiratory depression) when used with MAOIs, they do not typically trigger Serotonin Syndrome. They are generally considered safer than Pethidine or Fentanyl in this context, though caution is still advised. * **D. Buprenorphine:** This is a partial mu-opioid agonist. It does not possess significant serotonergic activity and is not classically associated with the severe excitatory reactions seen with Fentanyl or Pethidine. **High-Yield NEET-PG Pearls:** 1. **Pethidine (Meperidine)** is the most notorious opioid for causing Serotonin Syndrome with MAOIs; however, Fentanyl is the most relevant potent synthetic opioid with this risk. 2. **Clinical Triad of Serotonin Syndrome:** Cognitive changes (agitation/confusion), Autonomic hyperactivity (tachycardia/hyperthermia), and Neuromuscular abnormalities (clonus/rigidity). 3. **Treatment:** Immediate discontinuation of offending agents and administration of **Cyproheptadine** (5-HT2A antagonist). 4. **Avoid "The Big Four" with MAOIs:** Pethidine, Fentanyl, Tramadol, and Dextromethorphan.

Q: The 00 opioid receptor is responsible for which of the following effects?

Miosis. The **$\mu$ (Mu) opioid receptor** is the primary mediator for most clinical and adverse effects of opioid analgesics. ### **Explanation of the Correct Answer** **A. Miosis:** Opioids stimulate the **Edinger-Westphal nucleus** of the oculomotor nerve (CN III). This leads to parasympathetic overactivity, causing pupillary constriction (pinpoint pupils). Unlike many other opioid effects, tolerance does **not** develop to miosis, making it a reliable diagnostic sign of opioid overdose. ### **Analysis of Incorrect Options** * **B. Bradycardia:** While opioids can cause mild bradycardia via central vagal stimulation, this is more characteristic of the **$\kappa$ (Kappa)** receptor or specific drugs like Fentanyl. It is less a defining feature of the $\mu$ receptor compared to miosis. * **C. Hypothermia:** Opioids typically interfere with the thermoregulatory center in the hypothalamus. While $\mu$ receptors can cause a slight decrease in body temperature, **$\kappa$ receptors** are more specifically associated with significant hypothermia. * **D. Bronchodilation:** This is incorrect. Opioids can cause **bronchoconstriction** (especially Morphine) due to histamine release from mast cells. This is why Morphine is used with caution in bronchial asthma. ### **High-Yield NEET-PG Pearls** * **The "Rule of Two":** Tolerance does **not** develop to two specific opioid effects: **Miosis** and **Constipation**. * **$\mu$ Receptor Effects:** Supraspinal analgesia, respiratory depression (the most common cause of death in overdose), euphoria, and physical dependence. * **$\kappa$ Receptor Effects:** Spinal analgesia, miosis, dysphoria, and psychotomimetic effects (hallucinations). * **Diagnostic Triad of Opioid Poisoning:** Coma, Pinpoint pupils, and Respiratory depression.

Q: Which of the following statements about cyclooxygenase-2 (COX-2) is true?

COX-2 is inducible.. **Explanation:** The enzyme Cyclooxygenase (COX) exists in two primary isoforms: COX-1 and COX-2. Understanding their differences is high-yield for pharmacology. **1. Why Option B is Correct:** **COX-2 is an inducible enzyme.** While COX-1 is "constitutive" (constantly present in most tissues), COX-2 is normally absent or present in very low amounts. It is rapidly upregulated (induced) by inflammatory stimuli such as cytokines (IL-1, TNF-α), growth factors, and endotoxins. It is primarily responsible for synthesizing prostaglandins that mediate **pain, inflammation, and fever.** **2. Why the Other Options are Incorrect:** * **Option A:** Indomethacin is a **non-selective NSAID**. It inhibits both COX-1 and COX-2. Only "Coxibs" (like Celecoxib) are selective for COX-2. * **Option C:** This describes **COX-1**. COX-1 produces cytoprotective prostaglandins ($PGE_2$ and $PGI_2$) that maintain the gastric mucosal barrier and regulate renal blood flow. This is why non-selective NSAIDs cause gastric ulcers. * **Option D:** COX-2 is not limited to fetal tissues. While it is inducible in most places, it is **constitutively expressed** in specific adult organs, including the **Kidneys, Brain, and Spinal Cord.** **Clinical Pearls for NEET-PG:** * **The "Constitutive" Exception:** Remember that COX-2 is constitutive in the **Kidney** (macula densa) and **CNS**. This explains why selective COX-2 inhibitors can still cause renal side effects and hypertension. * **Cardiovascular Risk:** Selective COX-2 inhibitors (e.g., Rofecoxib) were associated with increased MI/Stroke risk because they inhibit $PGI_2$ (vasodilator/anti-aggregatory) in endothelium without inhibiting $TXA_2$ (vasoconstrictor/pro-aggregatory) in platelets (which is COX-1 dependent). * **Glucocorticoids:** These drugs exert their anti-inflammatory effect partly by inhibiting the expression of the COX-2 gene.

Q: Morphine withdrawal is characterized by all EXCEPT?

Miosis. The correct answer is **A. Miosis**. Morphine withdrawal is characterized by a "rebound" phenomenon where the body’s physiological processes, previously suppressed by the opioid, become hyperactive. Morphine (an opioid agonist) causes **miosis** (pinpoint pupils) during acute action via stimulation of the Edinger-Westphal nucleus. Conversely, during **withdrawal**, the sympathetic nervous system becomes overactive, leading to **Mydriasis** (pupillary dilation), not miosis. [2] **Analysis of Options:** * **B. Yawning:** This is one of the earliest and most characteristic signs of opioid withdrawal, often accompanied by sneezing and rhinorrhea. [2] * **C. Lacrimation:** Excessive tearing (lacrimation) and sweating (diaphoresis) occur due to autonomic hyperactivity during the withdrawal phase. * **D. Diarrhoea:** Opioids are known to cause constipation by slowing GI motility. [1] During withdrawal, the GI tract becomes hypermotile, leading to abdominal cramps and profuse diarrhea. **Clinical Pearls for NEET-PG:** * **The "Cold Turkey" Sign:** Piloerection (goosebumps) occurs during withdrawal, giving the skin the appearance of a plucked turkey. [2] * **Miosis Exception:** While most opioids cause miosis, **Meperidine (Pethidine)** is an exception; it causes mydriasis due to its atropine-like (anticholinergic) action. [1] * **Treatment:** Acute withdrawal is managed with **Clonidine** (α2 agonist to reduce sympathetic overactivity) or substitution therapy with long-acting opioids like **Methadone** or **Buprenorphine**. * **Naloxone:** Administration of this antagonist in an opioid-dependent patient will precipitate "precipitated withdrawal," which is sudden and severe.

Q: Which of the following is a long-acting classical H1 antihistamine?

Chlorpheniramine. **Explanation:** The question asks for a **long-acting classical (1st generation)** H1 antihistamine. **1. Why Chlorpheniramine is Correct:** Chlorpheniramine is a potent 1st-generation antihistamine belonging to the alkylamine class. While many 1st-generation drugs (like Diphenhydramine) have a short duration of action (4–6 hours), Chlorpheniramine is characterized by a relatively long half-life (~20–24 hours in adults), allowing for less frequent dosing. It is "classical" because it crosses the blood-brain barrier, causing sedation and anticholinergic side effects. **2. Analysis of Incorrect Options:** * **Astemizole:** This is a **2nd-generation** antihistamine. While it is exceptionally long-acting (half-life of days), it is no longer used clinically due to the risk of fatal arrhythmias (*Torsades de Pointes*) caused by QT interval prolongation. * **Cetirizine:** This is a **2nd-generation** antihistamine (a metabolite of Hydroxyzine). It is "non-sedating" (or minimally sedating) and does not fall under the "classical" category. * **Clemastine:** This is a 1st-generation antihistamine (ethanolamine class). However, it generally has a shorter duration of action compared to the sustained effect of Chlorpheniramine. **3. NEET-PG High-Yield Pearls:** * **1st Gen vs. 2nd Gen:** 1st generation drugs are lipophilic (cross BBB) and cause sedation/anticholinergic effects. 2nd generation drugs are lipophobic and lack these effects. * **Cardiac Toxicity:** Astemizole and Terfenadine were withdrawn because they inhibit delayed rectifier K+ channels in the heart. * **Active Metabolites:** Fexofenadine is the active metabolite of Terfenadine; Cetirizine is the active metabolite of Hydroxyzine; Loratadine is metabolized to Desloratadine. * **Drug of Choice:** Chlorpheniramine is often the preferred antihistamine for allergic reactions in pregnancy (Category B).

Q: Low-dose aspirin inhibits the formation of which substance?

Thromboxane A2. ### Explanation **Mechanism of Action:** Aspirin (Acetylsalicylic acid) is an irreversible inhibitor of the enzyme **Cyclooxygenase (COX)**. It works by acetylating a serine residue at the active site of the enzyme. While high doses of aspirin inhibit both COX-1 and COX-2 globally, **low-dose aspirin (75–150 mg/day)** exhibits a preferential and irreversible inhibition of **COX-1 in platelets**. Platelets lack a nucleus and cannot synthesize new enzymes. Therefore, the inhibition of COX-1 lasts for the entire lifespan of the platelet (approx. 8–11 days). This prevents the conversion of arachidonic acid into **Thromboxane A2 (TXA2)**, a potent vasoconstrictor and platelet aggregator. This specific biochemical effect is the basis for aspirin’s use as an antiplatelet agent. **Analysis of Incorrect Options:** * **Option A (PGF2α):** While aspirin can inhibit the synthesis of various prostaglandins at higher anti-inflammatory doses, low-dose aspirin is specifically titrated to target platelet TXA2. * **Option C (PGI2/Prostacyclin):** PGI2 is produced by vascular endothelial cells. Unlike platelets, endothelial cells have nuclei and can regenerate new COX enzymes. Therefore, at low doses, the synthesis of PGI2 (a vasodilator and anti-aggregator) is relatively spared or only transiently affected, maintaining a favorable antithrombotic balance. * **Option D:** Incorrect because the selectivity for TXA2 is the hallmark of low-dose therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Zero-order kinetics:** Aspirin follows first-order kinetics at low doses but shifts to zero-order kinetics at high/toxic doses. * **Reye’s Syndrome:** Aspirin is contraindicated in children with viral infections (except in Kawasaki disease). * **Aspirin Triad (Samter’s Triad):** Asthma, Nasal polyposis, and Aspirin hypersensitivity. * **Primary Prevention:** Low-dose aspirin is used to reduce the risk of Myocardial Infarction (MI) and Stroke.

Q: Which of the following drugs does not inhibit the COX pathway?

Betamethasone. The question asks to identify the drug that does not inhibit the **Cyclooxygenase (COX)** pathway. The COX pathway is responsible for converting arachidonic acid into prostaglandins and thromboxanes, which are key mediators of inflammation and pain. **Why Betamethasone is the correct answer:** Betamethasone is a potent **Glucocorticoid (Corticosteroid)**. Unlike Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), corticosteroids do not directly inhibit the COX enzyme [2]. Instead, they act further upstream in the inflammatory cascade by inducing the synthesis of **Lipocortin-1 (Annexin A1)**. Lipocortin-1 inhibits the enzyme **Phospholipase A2**, thereby preventing the release of arachidonic acid from the cell membrane [2]. By cutting off the supply of the precursor, corticosteroids suppress both the COX and the LOX (Lipoxygenase) pathways. **Why the other options are incorrect:** * **Aspirin:** A salicylate that irreversibly inhibits COX-1 and COX-2 by acetylating a serine residue at the active site [1]. * **Indomethacin:** A potent, non-selective reversible inhibitor of COX-1 and COX-2, commonly used in the management of PDA (Patent Ductus Arteriosus) and gout [1]. * **Diclofenac:** A phenylacetic acid derivative that is a non-selective COX inhibitor, widely used for musculoskeletal pain [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Upstream Inhibition:** Corticosteroids (like Betamethasone) inhibit **Phospholipase A2**, whereas NSAIDs inhibit **COX** [2]. * **Dual Pathway Suppression:** Because corticosteroids inhibit Phospholipase A2, they decrease both **Prostaglandins** (COX pathway) and **Leukotrienes** (LOX pathway) [2]. * **Aspirin Uniqueness:** It is the only NSAID that binds **irreversibly** to the COX enzyme; all others are reversible [1]. * **Steroid Potency:** Betamethasone and Dexamethasone have minimal mineralocorticoid activity and are long-acting glucocorticoids.

Question 1

Which of the following statements about bradykinin is true?

Accepted Answer

Causes pain

Answer

Causes bronchodilation

Answer

Causes vasoconstriction

Answer

Decreases vascular permeability

Question 2

Which opioid is contraindicated in patients taking MAO inhibitors?

Accepted Answer

Fentanyl

Answer

Codeine

Answer

Morphine

Answer

Buprenorphine

Question 3

The 00 opioid receptor is responsible for which of the following effects?

Accepted Answer

Miosis

Answer

Bradycardia

Answer

Hypothermia

Answer

Bronchodilation

Question 4

Which of the following drugs has the least gastrointestinal toxicity?

Accepted Answer

Paracetamol

Answer

Indomethacin

Answer

Aspirin

Answer

Phenylbutazone

Question 5

Which of the following statements about cyclooxygenase-2 (COX-2) is true?

Accepted Answer

COX-2 is inducible.

Answer

COX-2 is not inhibited by indomethacin.

Answer

COX-2 generates cytoprotective prostaglandins in the gastric mucosa.

Answer

COX-2 is found only in fetal tissues.

Question 6

Morphine withdrawal is characterized by all EXCEPT?

Accepted Answer

Miosis

Answer

Yawning

Answer

Lacrimation

Answer

Diarrhoea

Question 7

Which of the following is a long-acting classical H1 antihistamine?

Accepted Answer

Chlorpheniramine

Answer

Astemizole

Answer

Cetirizine

Answer

Clemastine

Question 8

Low-dose aspirin inhibits the formation of which substance?

Accepted Answer

Thromboxane A2

Answer

Prostaglandin F2

Answer

Prostaglandin I2

Answer

All of the above

Question 9

All of the following are true regarding acetaminophen EXCEPT:

Accepted Answer

Approximately 95% of acetaminophen undergoes detoxification by CYP2E1.

Answer

It is the most commonly used analgesic.

Answer

In severe doses, liver failure may occur.

Answer

Injury to the liver is produced by NAPQI.

Question 10

Which of the following drugs does not inhibit the COX pathway?

Accepted Answer

Betamethasone

Answer

Aspirin

Answer

Indomethacin

Answer

Diclofenac

Analgesics and Anti-inflammatory Drugs — MCQs

Analgesics and Anti-inflammatory Drugs — MCQs

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